Tsukamoto Kindergarten, a preschool in Osaka city, Japan, is being investigated for allegedly handing out flyers containing hate speech against Koreans living in Japan and against Chinese people, Kyodo News reported on Thursday.

"Korean residents in Japan and Chinese people are devious," read the flyer that the kindergarten allegedly distributed.

Kyodo News also pointed out that the flyer called Chinese people "shinajin," a derogatory term.

The kindergarten is known to have sent out flyers in December 2016, criticizing Korean residents in Japan.

"The problem is that people, who are Korean at heart, reside in Japan as Japanese," read the flyer.

The school has previously been criticized for making students memorize the "Imperial Edict on Education," used during Japan's imperial rule of other countries.

During a field day in 2015, the school also allegedly made students take an oath blaming Korea and China for making Japan a malevolent nation.

The controversy deepened when it was revealed that the kindergarten also runs an elementary school just outside Osaka where Akie Abe, wife of Prime Minister Shinzo Abe, is an honorary principle.

Authorities in Osaka Prefecture have warned the kindergarten that the flyers are a violation of the "Anti-Hate Speech Bill" passed in June 2016.

The bill defines hate speech as "unjust, discriminatory statements and actions involving insults or threats to injure or kill with the purpose of promoting and spreading discrimination and the exclusion of foreign residents and their children from the community."

Meanwhile, the kindergarten refused to explain to Osaka Prefecture authorities why it distributed such flyers, saying it is involved in a legal suit with parents.